Thorpe, Steven J.

Research Areas

Research is focused on the properties of surfaces and interfaces through examination of the chemical, electrochemical, and structure-chemical interactions that occur in materials. A brief summary of current research areas follows.

Production of Amorphous and Nanocrystalline Thin Films

The production of novel amorphous and nanocrystalline materials is underway using multiple techniques.  For thick films (~40 μm), UHV planar flow casting is used to produce materials in the form of ribbons for use as electrocatalysts in alkaline fuel cells, PEM fuel cells and electrolysers. For thin film (~50 nm), production, deposition on a substrate is achieved using a UHV PVD ion beam deposition system. Production of amorphous and nanocrystalline films of Ni, Fe, Cr, Ag, Au and their alloys have been produced for use in the surface modification of biomaterials, for studying dealloying in producing nanoporous materials and as corrosion barriers and electrocatalysts in alternate energy technologies. A new class of amorphous materials, bulk metallic glasses having very high elastic moduli and stiffness, are also under investigation using suction casting linked to a vacuum arc melting apparatus.  Most recently, amorphous and nanocrystalline powders have been produced by a combination of cryomilling and surfactant assisted high energy ball milling for use as electrocatalysts in AEM water electrolysis

Characterization of Amorphous and Nanocrystalline Metal

Upon fabrication of amorphous metals or nanocrystalline materials, various tools are used to characterize their multi scale structure including scanning electron microscopy (SEM), x-ray diffraction (SRD), scanning transmission electron microscopy(STEM) in combination with extended x-ray absorption fine structure (EXAFS). The general and localized corrosion resistance of these alloys is being assessed using a wide variety of polarization techniques: potentiodynamic, potentiostatic, pit propagation rate testing, electrochemical potentiokinetic reactivation testing and impedance spectroscopy. The thermal stability and effects of devitrification of these glassy alloys into multiphase or nanocrystalline supersaturated solid solutions is explored using differential scanning calorimetry (DSC). The localized corrosion resistance of these films is closely related to their oxide film chemistries and their role in passivity and localized corrosion using x-ray photoelectron spectroscopy (XPS) has been elucidated. These materials may have use as surface modified coatings in biomaterials and advanced metallization in microelectronics, e.g. the usefulness of these coating in preventing corrosion of stents.

Amorphous Metal / Nanocrystalline Electrocatalysis

Amorphous metals are a unique class of materials, possessing novel surface chemistry properties rendering then ideal for use in surface related industries of heterogeneous catalysis and sensors. The development of anode and cathode materials for hydrogen fuel cells and electrolysers, methanol fuel cells and chlorine evolution as a function of anode chemistry and surface treatment offering enhanced reactivity and selectivity is under investigation. Novel chemical activation treatments have been developed which yield activated catalyst surfaces with excellent stability in alkaline environments. Some insight into the modification of catalyst surface chemistry through chemical treatment has been achieved by in-situ Raman spectroscopy, ultraviolet photoelectron spectroscopy (UPS) EXAFS, and XPS. The electrocatalytic properties of nanocrystalline materials made by devitrification of metallic glasses and sputtering are also being investigated via the techniques described above and through actual AEM electrolysers and fuel cells.

Template Synthesis of Nanowires and Nanotubes

Work continues in the fabrication, structural and electrochemical characterization of metallic nanowires and nanowires with controlled sizes and geometries over the size range of 5 to 800 nm. These nanostructures have potential for use in many areas such as electrocatalysis, electronics, optoelectronics, photonics, information storage, energy conversion, fluid transportation and drug release along with chemical and biological sensing.

Research Clusters

• Computational Material & Data Analytics

• Coatings & Surfaces

• Additive & Advanced Manufacturing

• Energy Generation & Storage